ONITEBSITY  OF   CALIFORNIA   PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


INVESTIGATIONS   WITH 
MILKING   MACHINES 


BY 

F.  W.  WOLL 


BULLETIN  No.  311 

September,  1919 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY 

1919 


EXPERIMENT  STATION  STAFF 
Heads  of  Divisions 

Thomas  Forsyth  Hunt,  Dean. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Walter  Mulford,  Forestry,  Director  of  Resident  Instruction. 

Herbert  J.  Webber,  Director  Agricultural  Experiment  Station. 

B.  H.  Crocheron,  Director  of  Agricultural  Extension. 
Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

James  T.  Barrett,  Acting  Director  of  Citrus  Experiment  Station;  Plant  Pathology. 

William  A.  Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 

Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

Fritz  W.  Woll,  Animal  Nutrition. 

W.  P.  Kelley,  Agricultural  Chemistry. 

H.  J.  Quayle,  Entomology. 

Elwood  Mead,  Rural  Institutions. 

H.  S.  Reed,  Plant  Physiology. 

J.  C.  Whitten,  Pomology. 

Frank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 

F.  L.  Griffin,  Agricultural  Education. 
John  E.  Dougherty,  Poultry  Husbandry. 
S.  S.  Rogers,  Olericulture. 
L.  J.  Fletcher,  Agricultural  Engineering. 
Edwin  C.  Voorhies,  Assistant  to  the  Dean. 


Division  of  Animal  Husbandry 

G.  H.  True  F.  W.  Woll 

J.  I.  Thompson  J.  F.  Wilson 

C.  V.  Castle  P.  I.  Dougherty 
G.  H.  Wilson 


INVESTIGATIONS  WITH  MILKING  MACHINES 


F.  W.  WOLL 


Milking  machines  have  now  been  successfully  operated  in  dairy 
herds  in  different  parts  of  the  country  for  more  than  a  quarter  of  a 
century,  and  in  many  dairies  several  generations  of  cows  have  been 
milked  by  machines  during  this  period.  Owing  to  the  difficulty  of 
securing  efficient  and  reliable  milkers  in  recent  years,  especially  while 
war  conditions  prevailed,  machine  milking  has  been  adopted  in  a  rapidly 
increasing  number  of  American  dairies  during  this  period,  and  there  are 
now  perhaps  few  dairy  sections  in  the  country  where  milking  machines 
have  not  been  installed  and  are  operated  successfully. 

Practical  experience  with  milking  machines  and  numerous  investiga- 
tions of  the  work  of  different  makes  of  machines  conducted  by  experi- 
ment stations  during  the  last  decade  or  two  have  fully  established  the 
practicability  and  the  economy  of  modern  milking  machines  by  this 
time;  as  a  result,  there  is  at  present  a  constant  and,  in  many  sections, 
a  rather  rapid  transition  from  hand  to  machine  milking  in  American 
dairy  herds.  This  transition  is  retarded  in  some  cases  by  a  doubt  in 
the  minds  of  dairy  farmers,  perhaps  especially  by  owners  of  valuable 
pure-bred  herds,  as  to  whether  the  cows  will  do  quite  as  well  when 
milked  by  machine  as  by  hand,  and  whether  machine  milking  will  not 
necessarily  have  a  tendency,  at  least  in  the  case  of  some  cows,  to  reduce 
their  milk  production  for  entire  lactation  periods  as  compared  with  hand 
milking,  even  if  this  would  not  be  sufficiently  marked  to  interfere  ap- 
preciably with  their  future  usefulness  as  dairy  producers.  Failures  of 
certain  milking  machines  in  the  case  of  individual  herds,  and  the  fact 
that  conditions  and  results  obtained  in  other  sections  are  not  known, 
doubtless  account  for  this  questioning  by  some  dairy  farmers  of  the 
practical  value  of  milking  machines. 

The  investigations  of  milking  machines  in  the  University  dairy  herd 
reported  in  this  bulletin  were  commenced  in  the  spring  of  1915  with  a 
special  view  to  ascertaining  the  effect  of  long  periods  of  machine  milking 
on  the  dairy  production  of  cows.  The  plan  of  the  investigations 
especially  aimed  at  furnishing  definite  evidence  on  the  question  of 
whether  or  not  machine  milking  involves  any  risk  in  regard  to  the  con- 
tinued efficiency  of  dairy  cows,  and  the  results  should  be  of  special 


32  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

interest  and  value  to  dairymen  who  may  be  more  or  less  in  doubt  with 
regard  to  this  point.  It  is  believed  that  the  results  herewith  presented 
will  also  be  of  value  to  other  dairy  farmers  who  have  not  as  yet  seriously 
considered  the  matter  of  installing  milking  machines  in  their  herds,  and 
will  clear  up  various  points  in  connection  with  the  operation  of  the 
machines,  concerning  which  there  may  be  a  question. 

At  the  time  this  investigation  was  commenced  there  were  at  least 
three  different  makes  of  milking  machines  on  the  market  in  this  country 
that  had  been  found  to  do  satisfactory  work  when  operated  in  accor- 
dance with  the  direction  of  manufacturers,  and  that  had  been  more  or 
less  thoroughly  investigated  by  American  experiment  stations.  Con- 
siderable literature  on  the  subject  of  milking  machines  had  been  pub- 
lished by  these  stations  which,  generally  speaking,  furnished  conclusive 
evidence  as  to  the  value  of  this  method  of  milking.  During  the  last 
three  years  the  number  of  different  milking  machines  placed  on  the 
market,  and  the  published  reports  of  investigations  of  these  have  been 
further  increased  (see  partial  bibliography,  pp.  54) ;  frequent  discussions 
on  the  subject  of  machine  milking  in  our  agricultural  and  dairy  press 
have  likewise  greatly  enlarged  our  knowledge  of  different  types  of  milk- 
ing machines  and  of  their  practicability  under  present  conditions  of 
dairying. 

Two  different  makes  of  machines  were  employed  in  this  investiga- 
tion, viz.,  the  " Calf- Way"  Milker,  during  the  first  three  years,  and  the 
Empire  Milking  Machine  for  the  past  year,  operated  either  alone  or 
along  with  the  "  Calf- Way  "  Milker.  The  latter  machine  is  an  improved 
type  of  the  Hazelwood  milking  machine,  which  was  manufactured  by 
a  Spokane,  Washington,  firm  and  introduced  in  a  number  of  western 
dairy  herds  about  a  dozen  years  ago.*  The  direct  occasion  for  taking 
up  this  study  was  the  fact  that  no  report  on  the  character  of  the  work 
done  with  the  " Calf- Way"  Milker  had  been  published  at  the  time. 
Gradually,  however,  the  investigation  was  broadened  so  as  to  cover  the 
scope  stated  above.  At  first  one  string  of  cows  in  the  University  dairy 
herd  was  milked  by  machine  and  the  balance  by  hand,  but  during  the 
last  year  and  a  half  nearly  all  milch  cows  in  the  herd  were  milked  by 
machine  throughout  the  lactation  period. 

*The  state  agents,  with  addresses,  of  these  two  and  other  milking  machines  at 
present  on  the  market  in  this  state  are  as  follows: 

Burrell  (B-L-K);  Baker,  Hamilton  &  Pacific  Co.,  San  Francisco. 
" Calf-Way";  Calf- Way  Milker  Co.,  San  Francisco. 
De  Laval;  De  Laval  Dairy  Supply  Co.,  San  Francisco. 
Empire;  J.  N.  Blair  &  Co.,  Sacramento. 
Hinman,  C.  F.  Daniells,  Hughson,  Cal. 
Perfection,  H.  F.  Lingg  Co.,  1901  Grant  Street,  Berkeley. 
Sharpies;  The  Sharpies  Separator  Co.,  San  Francisco. 
Universal;  California  Hydraulic  Engineering  Co.,  San  Francisco. 


INVESTIGATIONS   WITH    MILKING    MACHINES  33 

The  general  plan  of  the  experiments  was  to  continue  the  cows  on 
the  milking  machine  for  one  or  more  complete  lactation  periods  so 
as  to  secure  accurate  data  as  regards  the  total  milk  production  and 
the  rate  of  decrease,  if  any,  in  the  milk  flow  during  the  lactation  that 
may  result  from  machine  milking.  Data  concerning  the  immediate 
effect  of  changes  in  the  method  of  milking  practiced,  from  hand  to 
machine  and  vice  versa,  were  also  obtained.  The  milk  from  each  milk- 
ing for  the  individual  cows  was  weighed  and  sampled  separately,  com- 
posite samples  for  each  cow  being  tested  regularly  once  a  week  for  con- 
tent of  solids  and  butter  fat;  bacteriological  examinations  of  the  milk 
from  individual  cows  were  also  made  from  time  to  time  to  determine 
to  what  extent  milk  drawn  by  machine  comes  up  to  modern  sanitary 
standards. 

During  the  progress  of  this  investigation  a  total  of  78  cows  were 
machine-milked  for  periods  ranging  from  a  few  weeks  to  three  complete 
lactation  periods.  The  cows  included  34  grades  (mostly  grade  Hol- 
steins),  and  the  following  number  of  pure-breds:  20  Holsteins,  12  Jerseys, 
10  Guernseys  and  2  Ayrshires.  The  method  of  milking  adopted  for  a 
given  period  in  case  of  individual  cows  was  at  times  necessarily  deter- 
mined by  other  considerations  than  those  coming  within  the  plan  of 
this  investigation;  with  pure-bred  cows  especially  by  the  chances  of 
their  making  creditable  yearly  records;  but  in  the  main  the  original 
plan  was  adhered  to  insofar  as  cows  were  generally  milked  by  machine 
for  one  or  more  complete  lactation  periods. 

In  comparing  the  results  obtained  by  machine  milking  with  those 
obtained  by  hand  milking  for  the  cows  included  in  the  investigation, 
data  showing  the  immediate  effect  of  a  change  from  hand  to  machine 
milking,  and  vice  versa,  will  be  presented,  followed  by  data  for  entire 
lactation  periods. 

Immediate  Effect  of  a  Change  in  the  Method  of  Milking 

The  immediate  effect  of  the  method  of  milking  practiced  may  be 
traced  from  the  results  for  the  production  of  milk  and  butterfat  for  two 
weeks  prior  to  and  following  the  period  of  machine  and  hand  milking, 
respectively,  as  shown  in  Table  I.  Periods  close  to  the  beginning  or 
to  the  end  of  a  lactation  period,  when  the  milk  production  was  either 
not  yet  up  to  normal  or  was  abnormally  low  because  of  the  cow  being 
dried  up,  were  excluded  from  the  compilations. 


34 


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36  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

It  will  be  noted  that  data  for  28  cows  (31  periods  in  all)  are  given  in 
Table  I  for  two  weeks  before  the  change  from  hand  to  machine  milking, 
and  for  the  first  and  the  second  two-week  periods  on  machine  milking.  The 
average  production  of  milk  during  these  periods  was  406 . 7  lbs.,  379 . 3  lbs. 
and  355 . 1  lbs.,  respectively;  a  difference  of  27 . 4  lbs.  between  the  average 
yield  during  the  last  two  weeks  on  hand  milking  and  the  first  two  weeks  on 
machine  milking,  and  of  24 . 2  lbs.  between  the  average  yield  during  the 
first  two  periods  on  machine  milking,  i.e.,  a  decrease  in  milk  production 
during  the  latter  periods  of  6 . 7  and  6.4  per  cent.,  respectively.  In  the 
same  way,  the  average  production  of  butter-fat  decreased  1.33  lbs. 
both  going  from  hand  milking  to  machine  milking  and  during  the  first 
two  periods  on  machine  milking : — a  percentage  decrease  of  8 . 4  and  9 . 1 
for  the  two  periods.  The  per  cent,  of  fat  in  the  milk  dropped,  on  the 
average,  .07%  on  the  second  period  and  .11%  on  the  third  period. 
All  but  four  cows  went  down  in  milk  going  from  hand  to  machine  milk- 
ing, and  all  but  two  went  down  going  from  the  first  to  the  second 
machine-milking  periods,  the  corresponding  figures  for  production 
of  butter-fat  being  ten  and  four.  As  regards  the  average  percentage  of 
butterfat,  it  will  be  seen  that  there  was  an  increase  during  period  II 
over  period  I  in  the  case  of  14  cows,  and  a  decrease  in  the  case  of  16 
cows;  no  change  occurring  in  the  quality  of  milk  from  one  and  two  cows 
for  periods  II  and  III,  respectively. 

Considering  now  the  data  presented  in  Table  II,  showing  the  im- 
mediate effect  of  changing  from  machine  to  hand  milking,  we  note 
that  the  average  production  of  milk  for  16  cows  (eighteen  trials)  on 
machine  milking  Was  204.1  lbs.;  on  first  hand-milking  period,  183.8 
lbs.;  and  on  second  hand-milking  period,  166.5  lbs.;  a  decrease  of 
9.9%  and  9.4%,  respectively,  in  production  of  milk,  during  periods 
II  and  III  the  decrease  in  production  of  butter  fat  for  these  periods 
being  8.1  and  9.5  per  cent.,  respectively. 

There  was,  therefore,  a  somewhat  smaller  decrease  in  the  average 
milk  production  during  the  first  period  of  hand  milking  following  ma- 
chine milking  than  during  the  second  hand-milking  period,  but  the  de- 
crease in  average  yield  of  butter  fat  was  slightly  higher  during  the 
latter  period,  both  absolutely  and  relatively,  than  going  from  machine 
milking  to  hand  milking. 

Comparing  the  results  given  in  this  table  with  those  obtained 
by  changing  in  the  opposite  direction,  from  hand  to  machine  milking, 
as  shown  in  Table  I,  it  will  be  noted  that  the  figures  for  the  decrease  in 
production  during  the  two  periods  following  the  change  in  the  method 
of  milking  differ  only  slightly.  There  was  a  somewhat  greater  decrease 
in  the  production  of  both  milk  and  butter  fat  on  changing  from  machine 


INVESTIGATIONS   WITH    MILKING    MACHINES  37 

to  hand  milking  than  when  a  change  in  the  opposite  direction  was  made. 
This  may  be  explained  from  the  fact  that  the  cows  included  in  the  latter 
compilation  were,  in  general,  farther  advanced  in  their  lactation  than 
those  furnishing  the  data  included  in  Table  I  (221  vs.  115  days  from 
freshening,  on  the  average,  at  the  beginning  of  the  first  period),  since 
the  normal  decrease  in  production,  as  a  general  rule,  is  greater  toward 
the  close  of  the  lacation  period  than  early  in  the  lactation. 

The  differences  in  the  amounts  of  milk  or  butter  fat  obtained  during 
brief  periods  immediately  following  a  change  from  hand  to  machine 
milking,  or  vice  versa,  are  on  the  whole  not  sufficiently  marked  to  fur- 
nish an  argument  either  for  or  against  machine  milking.  In  the  case 
of  some  cows,  a  somewhat  increased  production  will  be  obtained  by 
machine  milking,  as  an  immediate  effect  of  the  change  in  the  method 
of  milking.  With  other  cows,  the  opposite  will  hold  true,  and  this  is 
perhaps  more  likely  to  be  the  case. 

As  in  the  case  of  the  change  from  hand  to  machine  milking,  there 
was  a  more  or  less  marked  decrease  in  production  during  the  first  two 
weeks  after  the  change  in  the  opposite  direction  was  made;  in  sixteen 
and  fourteen  cases  out  of  eighteen  there  was  a  decrease  in  milk  and  butter 
fat  production,  respectively,  during  period  II  as  compared  with  period 
I,  indicating  that  the  immediate  result  of  any  change  in  the  method  of 
milking  practised  is  likely  to  react  unfavorably  in  the  case  of  a  large 
majority  of  cows, — a  matter  well  understood  by  observing  dairymen, 
both  as  relating  to  a  change  in  the  method  of  milking  and  to  a  change 
in  milkers. 

However,  the  immediate  effect  of  the  method  of  milking  practised 
is  of  much  less  importance  than  the  effect  on  the  continued  production 
of  the  cows  during  an  entire  lactation,  or  during  several  lactation  periods. 
The  influence  of  the  method  of  milking  practised  on  the  production 
of  the  cows  during  long-continued  periods  will  now  be  considered. 
This  may  be  traced  in  two  ways,  viz., — from  the  gradual  decrease  in 
production  during  successive  brief  periods  of  the  lactation,  or  from  the 
total  production  during  the  entire  lactation.  The  results  obtained  in 
this  investigation  along  both  these  lines  have  been  compiled  and  are 
presented  and  discussed  in  the  following  pages. 

Decrease  in  Production  During  Lactation  Period 

Studies  of  the  production  of  milk  and  butter-fat  by  dairy  cows  with 
the  lactation  period  have  shown  that,  after  the  maximum  production 
has  been  reached  shortly  after  freshening,  there  is,  as  a  general  rule,  a 
gradual  decrease  in  production  as  the  lactation  period  advances.  The 
exact  stage  of  maximum  production  will  vary  with  different  cows, 


38 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


and  even  with  the  same  cows,  with  their  body  condition  at  the  time  of 
freshening,  and  with  the  system  of  feeding  adopted.  It  will,  in  most 
cases,  come  within  a  couple  of  weeks  from  freshening,  but  sometimes 
occurs  several  weeks  later.  From  this  time  on,  there  is,  as  a  rule,  a 
rather  regular  decrease  in  production  for  a  period  of  six  to  eight  months, 
and  the  decrease  then  becomes  more  marked  until  the  cows  are  dried 
up,  during  the  tenth  to  eleventh  month  of  the  lactation.  The  per- 
centage of  monthly  decrease  during  the  main  part  of  the  lactation 
period  in  the  case  of  good  dairy  cows  has  been  found  to  amount  to  about 
5%  of  the  yield  of  the  preceding  month  and,  during  the  last  part  be- 
comes ten  to  twenty  per  cent,  of  the  production  during  the  preceding 
month.* 

The  methods  of  feeding,  milking,  and  handling  of  the  cows  will  de- 
termine to  an  appreciable  extent  the  persistency  of  the  milk  flow  and 
the  length  of  the  lactation  period,  the  smallest  percentage  decrease 
being  obtained  in  herds  composed  of  good  dairy  cows  that  are  fed  liberal 
rations,  carefully  milked,  and  are,  in  general,  subject  to  conditions 
most  favorable  to  a  continued  large  dairy  production. 


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FOUR-WEEK  PERIODS 


Fig.  1 


*Wis.  Station  Bulletin  102  and  Research  Bulletin  26;  Geneva  (New  York)  Station 
Report  1886,  p.  21;  Kentucky  Station  Bulletin  106;  California  Station  Bulletin  301. 


INVESTIGATIONS   WITH    MILKING    MACHINES 


39 


Complete  data  bearing  on  this  point  are  available  for  about  fifty 
cows  in  the  university  dairy  herd,  for  machine  and  hand  milking,  respec- 
tively. The  following  summary  tables  show  the  average  daily  yields 
of  milk  and  butter-fat  for  successive  periods  of  four  weeks  each,  for  all 
cows  that  gave  milk  during  ten  and  eleven  4-week  periods.  Data  for 
the  latter  cows  are  included  in  the  second  part  of  the  table.  The 
percentage  decrease  in  production  by  the  two  groups  for  successive 
months  are  also  given. 


Table  III. — Percentage  Decrease 

in  Production  During  Lactation 

Period  for  4- Week  Periods 

Ave. 

daily 

Ave. 

daily 

mi 

Ik 

Decrease 

butterfat 

Decrease 

yield 

,  lbs. 

in  per 

cent. 

yield 

,  lbs. 

in  per 

cent. 

Mach. 

Hand 

Mach. 

Hand 

Mach. 

Hand 

Mach. 

Hand 

No.  of  cows  included 

54 

52 

54 

52 

1st  4-week  period 

31.9 

34.7 

1.17 

1.42 

2nd  4-week  period 

29.2 

33.7 

8 

3 

1.05 

1.34 

10 

6 

3rd  4-week  period 

26.5 

31.3 

9 

7 

.97 

1.25 

8 

7 

4th  4-week  period 

23.9 

28.7 

10 

8 

.90 

1.16 

7 

7 

5th  4-week  period 

22.5 

26.6 

6 

7 

.84 

1.08 

7 

7 

6th  4-week  period 

20.8 

24.7 

8 

7 

.79 

1.01 

6 

6 

7th  4-week  period 

19.4 

22.8 

7 

8 

.74 

.93 

6 

8 

8th  4-week  period 

17.8 

20.4 

8 

11 

.70 

.85 

5 

9 

9th  4-week  period 

16.1 

18.2 

10 

11 

.64 

.76 

9 

11 

10th  4-week  period 

14.1 

15.3 

11 

16 

.57 

.66 

11 

14 

Difference,  l-5th  mo. 

29.5 

23.3 

28.2 

23.9 

l-10th  mo 

54.9 

55.9 

48.7 

53.5 

No.  of  cows  included 

43 

41 

43 

41 

1st  4-week  period 

31.3 

35.9 

1.18 

1.46 

2nd  4-week  period 

29.0 

35.2 

7 

2 

1.05 

1.39 

11 

5 

3rd  4-week  period 

26.4 

32.4 

9 

8 

.98 

1.28 

7 

8 

4th  4-week  period 

24.1 

29.8 

9 

8 

.91 

1.19 

7 

7 

5th  4-week  period 

23.0 

27.4 

5 

8 

.86 

1.11 

5 

7 

6th  4-week  period 

21.3 

25.0 

7 

9 

.81 

1.04 

6 

6 

7th  4-week  period 

19.8 

23.6 

7 

6 

.76 

.95 

6 

9 

8th  4-week  period 

18.0 

21.2 

9 

10 

.71 

.88 

7 

7 

9th  4-week  period 

16.4 

19.2 

9 

9 

.66 

.80 

7 

9 

10th  4-week  period 

15.0 

16.5 

9 

14 

.60 

.71 

9 

11 

11th  4-week  period 

12.7 

13.7 

15 

17 

.52 

.61 

13 

15 

Difference,  l-5th  mo. 

26.5 

23.7 

27.1 

24.0 

1-1 1th  mo. 

59.4 

61.8 

55.9 

58.2 

The  data  for  the  percentage  decrease  in  production  presented  in 
Table  III  suggest  that  the  production  of  both  milk  and  butter  fat  by 
the  machine-milked  cows  decreased,  on  the  average,  somewhat  more 
rapidly  than  that  of  the  hand-milked  cows  during  the  early  months  of 
the  lactation  period,  and  that  it  was  somewhat  lower  during  the  latter 
part  of  the  same.     Between  the  first  and  the  fifth  monthly  period  the 


40  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

milk  production  went  down  29.5%  for  the  machine-milked  cows  that 
gave  milk  during  ten  complete  4-week  periods,  against  23 . 3%  for  the 
corresponding  hand-milked  group ;  the  decrease  in  production  of  butter 
fat  for  this  period  was  28 . 2%  for  the  machine-milked  cows  against  23.9% 
for  the  hand-milked  cows.  On  the  other  hand,  if  the  yields  during  the 
first  and  the  tenth  monthly  periods  be  compared,  it  will  be  seen  that 
the  machine-milked  cows  decreased  on  the  average  54.9%  in  milk  and 
48.7%  in  butter  fat,  against  55.9%  and  53.5%,  respectively,  for  the 
hand-milked  cows.  Results  agreeing  closely  with  these  were  obtained 
for  the  cows  in  milk  for  eleven  complete  4-week  periods. 

It  will  be  noted  that  the  average  daily  yields  of  milk  and  butter-fat 
for  hand  milking  given  in  the  table  are  always  somewhat  higher  than 
those  for  machine  milking,  the  reason  being  that,  when  milked  by  hand, 
the  cows  were  in  many  cases  fed  more  liberal  rations,  and  therefore 
produced  more  heavily  than  when  machine  milked,  as  will  be  seen 
presently.  Data  for  the  same  cows  were  included  in  both  groups  in 
many  cases,  but  the  two  groups  were  not  composed  of  the  same  cows; 
all  available  records  obtained  on  machine  milking  were  included  in 
the  compilations  given  in  Tables  III  and  IV  and  a  similar  number  of 
records  for  hand-milked  cows  in  the  herd  were  selected  at  random  for 
comparison  from  the  herd  records. 

The  average  quality  of  the  milk  produced  by  the  two  groups  of  cows 
will  be  seen  from  Table  IV. 

Table  IV. — Average  Per  Cent,  of  Fat  in  Milk  During  Successive  Periods 

Machine 

No.  of  cows  included 54 

1st  4-week  period 3.67 

2nd  4-week  period 3 .  60 

3rd  4-week  period 3.66 

4th  4-week  period 3.77 

5th  4-week  period 3.73 

6th  4-week  period 3.80 

7th  4-week  period 3.81 

8th  4-week  period 3.93 

9th  4-week  period 3.98 

10th  4-week  period 3.96 

11th  4-week  period 

1-5    increase  in  %  of  fat +.06       —.03         

1-10  increase  in  %  of  fat +.29       +.22         

1-5    increase  in  %  of  fat —.03       —.02 

1-11  increase  in  %  of  fat +.32       +.31 


Hand 

Machine 

Hand 

52 

43 

41 

4.09 

3.77 

4.07 

3.98 

3.62 

3.98 

3.99 

3.71 

3.95 

4.04 

3.78 

3.99 

4.06 

3.74 

4.05 

4.09 

3.80 

4.06 

4.08 

3.84 

4.03 

4.17 

3.94 

4.15 

4.18 

4.03 

4.17 

4.31 

4.00 

4.31 

4.09 

4.38 

INVESTIGATIONS   WITH    MILKING   MACHINES 


41 


It  will  be  noted  from  Table  IV  that  the  changes  in  the  average 
quality  of  milk  during  the  progress  of  lactation  periods  are  fully  normal 
and  quite  similar  in  the  case  of  both  machine  and  hand-milked  cows; 
they  are  apparently  independent  of  the  special  method  of  milking  prac- 
tised (see  figs.  1  and  2). 

4.5 


4.0 


3.5 


/\ 

Ig. 

4 

0 

j 

jf[ 

i— 

A'ilwu} 

=  ^ 

c#- 

-.5 

7 

n 

_    fric'iLie 

-)titki% 

5 
FOUR- 


Fig. 


6  7 

WEEK  PERIODS 

2 


It  is  of  interest  to  compare  the  results  given  in  Table  III  for  the 
rate  of  decrease  in  production  with  the  progress  of  the  lactation  period 
with  similar  data  obtained  in  dairy  herds  in  this  and  other  states.  We 
select  as  typical  the  average  data  secured  for  cows  entered  in  the  Cali- 
fornia State  Dairy  Cow  Competition  and  similar  findings  for  cows  in 
the  dairy  herd  of  the  Wisconsin  Experiment  Station,  and  in  pure-bred 
herds  owned  by  Wisconsin  farmers.*  Table  V  shows  the  results  secured 
in  these  investigations.  The  figures  for  the  average  decrease  in  pro- 
duction of  milk  and  butter  fat  during  successive  4-week  periods  of  the 
lactation  for  the  herds  included  in  these  investigations  have  been  cal- 
culated and  are  given  in  the  last  two  columns  of  the  table. 


Table  V. — Average  Decrease  in  Production  During  Progress  of 
Lactation  Period 


Cal.  Dairy 
Cow  Comp'tion 


Milk 

Ave.  yield  1st  mo.,  lbs 46.4 

Decrease  in  per  cent.: 

2nd  4  weeks +  1 

3rd  4  weeks 9 

4th  4  weeks 7 

5th  4  weeks 7 

6th  4  weeks 7 

7th  4  weeks 9 

8th  4  weeks 11 

9th  4  weeks 9 

10th  4  weeks 11 

Total  decrease,  l-5th  mo 20.7 

l-10thmo 51.1 


Butter- 
fat 

1.95 


+  1 

9 

5 

6 

6 

7 

9 

8 
11 

16.9 
45.1 


Wisconsin 
Station  Herds 


Milk 

31.0 

6 

7 

8 

5 

4 

7 
10 
11 

24.2 
54.5 


Butter- 
fat 

1.34 


10 
8 
7 
5 
2 
8 
6 
6 


26.9 
50.8 


Wisconsin 
Dairy  Herds 


Milk 

43.9 

5 

7 

6 

5 

5 

6 
10 
13 
20 

21.2 
56.3 


Butter- 
fat 

1.76 


7 

5 

5 

5 

5 

9 
11 
15 

21.0 
50.6 


Averages 


Milk 


7 

6 

5 

7 
10 
11 
16 

22.0 
54.0 


Butter- 
fat 


13 
21. 

48. 


*Cal.  Station  Bulletin  301 
letin  26. 


Wisconsin  Station  Bulletin  102  and  Research  Bui- 


42  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  figures  given  in  Table  V  were  in  practically  all  cases  obtained 
by  hand  milking  and  are  therefore  directly  comparable  to  the  results 
previously  given  that  were  obtained  by  this  method  of  milking  with 
cows  in  the  university  dairy  herd.  In  the  majority  of  cases  they  were 
obtained  with  pure-bred  cows  and  represent  the  best  modern  dairy 
practice  as  adopted  by  leading  dairymen.  Comparing  the  average 
data  given  in  the  last  two  columns  of  the  table  with  the  results  presented 
in  Table  III,  it  will  be  seen  that  the  latter  figures  for  the  decrease  in 
production  with  advancing  lactation,  as  well  as  between  the  first  and 
the  last  period  of  the  lactation  periods,  were  in  most  cases  slightly  higher 
than  the  former,  in  the  case  of  both  methods  of  milking.  This  is  only 
what  might  be  expected  from  the  conditions  under  which  the  milking 
was  done,  in  the  case  of  the  investigations  quoted  in  Table  V,  and  in 
our  own  milking-machine  trials.  As  above  suggested,  careful  milking 
was  doubtless,  as  a  rule,  practised  in  most  of  the  former  herds,  the  cows 
being  milked  by  the  owners  themselves  or  by  interested  help  who  fully 
appreciated  the  importance  of  their  work  for  the  development  of  ex- 
cellent dairy  qualities  in  cattle,  and  for  the  maintenance  of  a  large 
dairy  production. 

On  the  other  hand,  the  milking  in  the  university  dairy  herd  was,  as  a 
rule,  done  by  help  similar  to  that  available  in  other  dairy  districts  in 
the  state, — a  class  of  men  who  are  frequently  none  too  interested  in 
their  work  and  who  in  the  large  majority  of  cases  do  not  remain  a  long 
time  in  the  same  place.  This  class  of  laborers  are  not,  as  a  rule,  likely 
to  make  good  milking-machine  operators,  but  especially  during  the  war 
conditions  of  the  past  year  one  was  glad  to  be  able  to  secure  any  kind 
of  help.  Reference  to  the  problem  of  the  milker  is  made  here  in  order 
to  show  that  the  conditions  under  which  the  investigations  reported  in 

this  bulletin  were  conducted  were,  in  general,  similar  to  those  that 
prevail  in  most  of  the  dairies  in  the  state.  The  results  secured  are, 
therefore,  as  a  rule,  no  better  than  those  that  may  be  obtained  by 
California  dairy  farmers  in  general;  in  fact,  it  may  be  safely  stated  that 
they  are  not  as  good  as  those  which  a  dairyman  of  fair  intelligence  and 
resourcefulness,  who  milks  his  own  cows  or  who  has  competent  reliable 
help  may  count  on  by  machine  milking. 

We  have  seen  that  both  in  the  case  of  the  cows  in  the  university 
herd  giving  milk  during  ten  complete  4-week  periods  and  those  in  milk 
for  eleven  such  periods,  the  percentage  decrease  in  milk  production  as 
well  as  in  average  yield  of  butter-fat  during  the  entire  lactation  period 
was  slightly  higher  for  the  hand-milked  cows  than  for  those  milked  by 
machine,  an  average  difference  of  two  to  five  per  cent,  occurring  in  the 
production  of  butter  fat  and  of  one  to  two  per  cent,  in  the  production  of 


INVESTIGATIONS   WITH    MILKING   MACHINES  43 

milk,  both  in  favor  of  machine  milking.  These  figures  refer  to  the 
decrease  in  production  from  the  first  to  the  tenth  or  eleventh  month  of 
the  lactation  period,  respectively.  In  view  of  this  result,  it  becomes 
of  special  interest  to  investigate  how  the  total  production  of  the  cows 
for  the  entire  lactation  period  compares  when  the  cows  were  machine- 
milked  and  when  they  .were  milked  by  hand.  The  available  data  on 
this  point  are  presented  and  discussed  below. 

Comparison  of  Yields  for  Entire  Lactation  Periods 

In  order  to  ascertain  the  effect  of  the  special  method  of  milking 
practised  on  the  total  production  of  the  cows,  the  data  for  all  complete 
lactation  periods  when  the  cows  were  machine  milked  have  been  com- 
piled, and  the  average  production  for  a  corresponding  number  of  lacta- 
tion periods  for  hand-milked  cows  has  been  computed  from  the  records 
of  the  university  dairy  herd,  either  for  the  same  cows  when  data  for 
complete  normal  lactations  were  available,  or  for  other  cows  taken  at 
random  from  the  herd  record  book.  The  cows  included  in  these  com- 
pilations were  milked  by  one  or  the  other  method  during  entire  lactation 
periods,  with  only  a  few  exceptions,  as  noted  in  a  subsequent  table. 
Table  VI  shows  the  average  data  obtained  in  these  compilations  for 
machine-milked  and  for  hand-milked  cows. 

Table  VI. — Comparisons  of  Yields  for  Entire  Lactation  Periods 

Machine-  Hand- 

Milking  Milking 

No.  of  lactation  periods 56  56 

No.  of  different  cows 45  40 

Ave.  age,  years-months 3-7  5-0 

Ave.  length  of  lactation,  days 351  355 

Ave.  production  of  milk,  lbs 7385.5  7800.3 

Ave.  per  cent,  fat 3.84  4.14 

Ave.  production  of  butterfat,  lbs 283.56  322.91 

Corrected  for  difference  in  age 326.09  322.91 

Highest  production  of  milk,  lbs 12722.5  13443.0 

Lowest  production  of  milk,  lbs 3961.9  2670.1 

Highest  production  of  butterfat,  lbs 588.16  558.75 

Lowest  production  of  butterfat,  lbs 156.22  121.44 

Longest  lactation  period,  days 507  462 

Shortest  lactation  period,  days 284  254 

It  will  be  seen  from  the  figures  in  Table  VI  that  during  fifty-six 
lactation  periods  (for  forty-five  different  cows),  when  machine-milking 
was  practised,  the  cows  produced  an  average  of  7,385.5  lbs.  milk  and 


44  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

283.56  lbs.  butter  fat  (average  fat  content,  3.84%).  Similar  data  for 
fifty-six  lactation  periods  (forty  different  cows)  in  the  same  herd  on 
hand  milking  gave  an  average  production  of  7,800.3  lbs.  milk  and 
322.91  lbs.  butter  fat,  (average  fat  content  4.14%).  Since  the  two 
groups  of  cows  were  not  made  up  exactly  of  the  same  animals  it  cannot 
be  safely  assumed  that  the  differences  in  average  production  noted  were 
due  to  the  difference  in  the  method  of  milking  practiced.  There  are 
a  number  of  other  factors  that  would  tend  to  influence  the  production 
of  the  cows,  the  most  important  doubtless  being  the  age  of  the  animals 
making  up  the  two  groups.  The  machine-milked  group  included  about 
30  young  heifers,  mostly  grades,  which  have  been  milked  by  machine 
ever  since  they  were  added  to  the  herd  in  1916  and  1917,  while  less  than 
a  dozen  heifers  were  included  in  the  hand-milked  group.  This  factor 
would,  of  course,  tend  to  favor  the  production  of  the  group  of  hand-milk- 
ed cows.  The  average  age  of  the  cows  in  the  machine-milked  group  was 
slightly  over  33^  years,  against  five  years  for  the  hand-milked  cows.  It 
is  known  from  the  results  of  advanced-registry  tests  of  cows  of  different 
ages  belonging  to  the  various  dairy  breed  associations  that  cows  will 
increase,  on  the  average,  about  15%  in  production  from  V/i  to  5  years 
old.*  It  may  be  assumed,  therefore,  that  if  the  machine-milked  cows 
had  been  of  the  same  average  age  as  those  included  in  the  hand-milked 
group,  they  would  have  had  an  average  production  of  326 .  09  lbs.  butter 
fat  to  their  credit,  or  within  one  per  cent  the  same  production  as  the 
average  for  the  hand-milked  lot,  indicating  that  the  dairy  production  of 
the  cows  was  not  appreciably  influenced  by  the  special  method  of  milking 
practised. 

If  the  production  of  the  individual  cows  that  were  below  full-age 
be  corrected  on  basis  of  an  average  increase  of  from  30  to  5%,  for  cows 
two  to  four  and  a  half  years  old,  respectively,  (loc.  cit.),  and  the  cal- 
culated yields  of  butter  fat  per  lactation  for  mature  cows  thus  obtained, 
it  will  be  seen  that  the  average  production  for  the  machine-milked 
cows  was  337.94  pounds  and  for  the  hand-milked  ones  352.89  pounds. 
The  standard  deviation  in  the  production  of  the  former  cows  was  90.1, 
and  of  the  latter  114.2,  making  the  probable  error  of  the  mean  of  the 
annual  yeilds  of  butter  fat  for  machine-milked  cows  8.12,  and  for  the 
hand-milked  cows  10.3.  The  difference  between  the  probable  error 
of  the  two  means  (obtained  by  extracting  the  square  root  of  the  sum 
of  the  two  probable  errors  raised  to  the  second  power)  is  13.1,  which  is 
but  slightly  less  than  the  difference  between  the  mean  production  of 
the  two  groups  of  cows.  The  difference  between  the  mean  production 
divided  by  the  probable  error  is  14.95-13.1,  or  1.14.     The  probability 

*California  Station  Bulletin  301,  p.  163. 


INVESTIGATIONS  WITH   MILKING   MACHINES  45 

of  the  occurrence  of  a  deviation  of  this  magnitude  is  44.2.  There  is, 
therefore  a  very  slight  deviation  from  an  even  chance  that  the  difference 
in  the  yields  on  the  two  methods  of  milking  is  not  caused  by  the  special 
method  of  milking  practised,  but  is  practically  within  the  limits  of 
the  natural  variations  in  the  production  of  cows  kept  under  conditions 
similar  to  those  present  in  the  University  Dairy  herd. 

It  may  be  noted  incidentally  that  the  probable  error  of  the  mean 
in  the  case  of  the  hand-milked  cows  was  greater  than  that  of  machine- 
milked  cows,  viz.,  10.3  against  8.12.  The  explanation  of  this  is  doubt- 
less to  be  sought  in  the  more  intensive  feeding  practiced  in  the  case 
of  several  of  the  hand-milked  cows  during  the  lactation  periods  when 
they  were  on  Advanced-Registry  tests  (p.  45). 

Further  evidence  as  to  the  effect  of  machine-milkjng  on  the  milk 
secretion  may  be  obtained  from  a  study  of  the  production  of  the  cows 
in  the  dairy  herd  that  were  milked  by  both  methods  during  different 
lactation  periods.  Such  data  are  available  for  thirteen  cows  in  all, 
covering  eighteen  complete  lactation  periods  for  machine  milking  and 
twenty-one  lactation  periods  when  the  cows  were  milked  by  hand. 

The  main  data  relating  to  the  production  of  these  cows  are  included 
in  Table  VII,  the  last  two  lines  of  which  show  the  average  production 
per  cow  and  per  lactation  periods  for  both  methods  of  milking.  Owing 
to  a  variety  of  causes  beyond  our  control,  the  number  of  lactation 
periods  for  the  two  methods  differ  in  the  case  of  the  individual  cows, 
and  the  milking-machine  periods  sometimes  preceded  and  sometimes 
followed  periods  when  the  cows  were  milked  by  hand.  Only  with  four 
cows  did  the  machine-milking  periods  come  within  the  hand-milked 
periods,  or  vice  versa,  and  three  of  these  yielded,  on  the  average,  more 
milk  and  butter  fat  t>n  hand-milking  than  on  machine-milking.  The 
explanation  of  this  result  and  of  other  differences  in  the  production 
of  the  cows  on  the  two  methods  of  milking  lies  in  the  natural  variations 
in  the  dairy  production  of  cows  from  year  to  year.  These  variations 
are  due  to  various  causes,  some  of  which  are  well  understood  and  others 
but  imperfectly  so.  The  most  important  factor  in  the  case  of  good 
dairy  cows  is  doubtless  the  intensity  of  the  system  of  feeding  practised. 
In  this  respect  marked  differences  occurred  with  the  cows  whose  records 
are  presented  in  the  table.  Pure-bred  cows  in  the  university  dairy 
herd,  as  in  the  case  of  practically  all  dairy  herds,  have  generally  received 
special  treatment  when  tested  for  advanced-registry  records,  in  the  way 
of  liberal  allowances  of  concentrates  and  green  or  succulent  feed,  three 
or  even  four  times  a  day  milking,  etc.  They  were  also  placed  in  separate 
box  stalls,  which  under  the  conditions  present  in  our  dairy  necessitated 
their  being  milked  by  hand.     Several  of  the  cows  (most  of  them  included 


46 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


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48  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

in  the  hand-milked  group)  were  able  to  produce  more  milk  on  account 
of  these  favorable  conditions,  especially  the  heavier  system  of  feeding, 
than  if  they  had  been  kept  in  the  milking  barn  with  the  regular  string 
and  milked  by  machine. 

The  feed  records  for  the  cows  whose  production  is  given  in  Table  VII 
have  been  compiled.  None  of  these  cows  were  pastured  during  their 
milking  periods.  In  order  to  arrive  at  a  definite  figure  for  the  total 
feed  consumption  of  the  cows  during  the  lactation  period,  the  number 
of  feed  units  contained  in  the  rations  fed  has  been  calculated  and  sum- 
marized. The  equivalents  of  the  various  feeding  stuffs  fed  were  obtained 
according  to  the  feed-unit  system,  the  following  amounts  of  the  dif- 
ferent feeds  being  considered  one  feed  unit: — 

2 . 2  lbs.  alfalfa  hay 

6  lbs.  Indian  corn  or  sorghum  silage 

7  lbs.  green  alfalfa 

8  lbs.  green  barley,  oats  or  corn 
10      lbs.  beets 

12.5  lbs.  pumpkins 
1 . 1  lbs.  wheat,  bran,  oats,  or  dried  beet  pulp 
1      lb.    barley  or  cocoanut  meal 

.  9  lbs.  linseed  meal 

.  8  lbs.  cottonseed  meal 

Table  VIII  gives  the  results  of  these  compilations  for  the  thirteen 
cows  whose  records  of  production  are  given  in  the  preceding  table. 

Table  VIII. — Total  Number  of  Feed  Units  Supplied  in  Rations 

Machine-Milked  Hand-Milked 


Concen-  Concen- 

Roughage  trates  Total  Roughage  trates  Total 

Atlantis 3869  1941  5810  3810  2959  6769 

Santa 4652  4199  8851  4264  2120  6384 

Willowmoor 4527  3620  8147  4648  3521  8169 

Colantha 3926  2214  6140  3948  1563  5511 

Fayne 5547     19  5566  5026    5026 

F.  R.  Pearl 3981  2471  6452  3815  3402  7217 

Marigold 3646  1395  5041  4457  2532  6989 

Hannah 3950  2409  6359  3459  1745  5204 

Korndyke 4177  2624  6801  4123  3420  7543 

Agnes 5372  4236  9608  4008  5631  9639 

Jap 5956  5956  5006  5  5011 

Begonia 4241  4241  4118    4118 

Julie 4520  2349  6869  4209  2638  6847 

Average 4489  2114  6603  4222  2272  6494 


INVESTIGATIONS   WITH    MILKING   MACHINES  49 

If  the  data  for  the  total  feed  consumption  in  Table  VIII  be  compared 
with  the  production  of  the  respective  cows  when  milked  by  machine  or 
hand,  it  will  be  seen  that,  with  but  few  exceptions,  the  production  of 
milk  and  butter  fat  during  machine  or  hand-milked  periods  follows 
the  feed  consumption;  wherever  the  higher  production  occurs  for  a 
given  animal,  the  larger  amount  of  feed  eaten  will  be  found,  as  shown 
by  the  total  number  of  feed  units  consumed  during  the  lactation  period. 


Fig.  3. — Interested  Jap's  Santa,  296928,  owned  by  the  University  of  California. 

This  is  of  course  what  one  would  expect  and  is  only  referred  to  here 
for  the  sake  of  the  comparison  that  it  affords  of  the  amount  of  feed 
eaten  by  machine-milked  and  hand-milked  cows. 

Attention  may  be  called  in  this  connection  to  the  production  of 
the  pure-bred  Jersey  cow  Santa  (Interested  Jap's  Santa,  296928)  for 
the  lactation  period  beginning  September  12,  1915,  when  she  was 
milked  by  machine.  She  produced  during  this  lactation  period,  as  a 
three-year  old,  9052.5  lbs.  of  milk  and  588.16  lbs.  butter  fat  (average 
fat  content  6.50%).  During  the  following  lactation  period,  beginning 
March  13,  1917,  she  produced  on  hand  milking,  13308.5  lbs.  of  milk 
and  805.72  lbs.  fat  (6.05%  fat),  which  was  the  highest  record  of  pro- 


50  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

duction  for  a  Jersey  cow  in  the  state  until  the  next  lactation  period, 
just  completed,  when  she  produced  15,569.4  lbs.  milk  and  940.72  lbs. 
butter  fat.  Evidently  the  fact  that  this  cow  was  milked  with  machine 
for  an  entire  lactation  period  as  a  heifer  did  not  interfere  with  her 
capacity  for  an  even  larger  dairy  production  during  the  following  years 
(see  fig.  3) ;  on  the  other  hand,  however,  it  cannot  be  stated  definitely, 
that  the  increase  might  not  have  been  still  greater  if  she  had  not  been 
machine-milked  at  all. 

It  will  be  noted  from  Table  VII  that  the  average  figures  for  the  pro- 
duction of  the  cows  for  the  period  they  were  machine  milked  were  8,424 
lbs.  milk  and  350.00  lbs.  fat  (average  per  cent.,  4.15),  against  7,946.9 
lbs.  milk  and  336.28  lbs.  butter  fat  (average  per  cent.,  4.23)  for  periods 
of  hand-milking, — a  difference  of  5 . 6%  in  the  production  of  milk  and 
3 . 9%  in  the  production  of  butter  fat  in  favor  of  machine-milking.  If 
the  data  for  the  separate  lactation  periods  included  be  averaged,  it 
will  be  found  that  these  differences  between  the  two  groups  are  reduced 
to  4.3%  and  1.8%  for  the  production  of  milk  and  butter  fat,  res- 
pectively. The  average  age  of  the  cows  during  the  periods  of  hand- 
milking  was  somewhat  below  that  for  the  periods  of  machine-milking, 
but,  on  the  other  hand,  a  number  of  the  cows  were  fed  heavier  rations 
when  hand-milked  than  when  milked  by  machine  in  the  regular  string, 
for  the  reason  previously  stated.  The  extent  to  which  these  two 
factors  influenced  the  production  of  the  cows  cannot  be  determined 
with  certainty,  but  it  would  seem  that  they  were  of  nearly  equal  import- 
ance in  the  case  of  the  two  groups  of  cows.  A  study  of  the  data  pre- 
sented in  the  table  by  the  statistical  method  will  show  that  the  natural 
variations  in  yearly  production  by  the  cows  are  far  greater  than  the 
difference  between  their  average  production  when  machine-milked 
and  when  hand-milked.  The  same  conclusion  may  therefore  be  war- 
ranted from  a  consideration  of  the  data  presented  in  Table  VII  as  in 
the  case  of  those  in  Table  VI,  that  the  special  method  of  milking  prac- 
tised does  not,  on  the  whole,  affect  appreciably  the  dairy  production 
of  the  cows,  provided  the  milking  is  done  with  equal  care  in  either  case. 
This  result  is  fully  corroborated  by  investigations  of  the  efficiency  of 
milking  machines  conducted  by  other  experiment  stations,  notably  those 
of  the  Wisconsin  and  Geneva  (N.Y.)  stations.  According  the  the  latter 
station,*  "the  only  conclusion  possible  to  draw,  from  trials  extending 
over  five  years  and  including  a  large  number  of  lactation  periods,  is 
that  machine-milking,  if  properly  done,  does  not  influence  the  flow  of 
milk  to  any  extent  capable  of  measurement." 

♦Bulletin  353,  Nov.  1912. 


INVESTIGATIONS   WITH   MILKING   MACHINES  51 

The  fluctuations  in  milk  flow  that  frequently  occur  during  different 
lactation  periods  in  the  case  of  individual  cows  are  determined  by  a 
variety  of  factors,  as  previously  suggested;  of  these,  the  intensity  of 
the  system  of  feeding  adopted,  the  age,  and  the  " condition"  of  the  cow, 
are  of  marked  influence.  Evidently  the  method  of  milking  practised 
is  not  an  important  factor  in  determining  the  amount  of  milk  or  butter 
fat  obtained  during  the  lactation  period,  when  the  milking  is  carefully 
done.  Nearly  all  cows  take  readily  to  machine  milking,  especially 
young  heifers,  and  under  similar  conditions  they  will,  as  a  general  rule, 
yield  as  much  milk  when  milked  by  machine  as  by  hand  if  they  are 
always  promptly  stripped  by  hand  after  the  machine  is  removed.  Cases 
in  which  cows  do  not  do  well  on  machine-milking  are  very  exceptional, 
being  mostly  those  of  old  cows  of  a  nervous  disposition.  Such  cows, 
and  cows  that  cannot  very  well  be  milked  by  machine  on  account  of 
unusual  size  or  shape  of  teats  or  uneven  udders  are  preferably  milked 
by  hand  or  disposed  of  when  a  change  to  machine  milking  is  made  in 
a  herd. 

Summary 

The  modern  milking-machine  is  a  practical  and  safe  labor-saving- 
device.  This  has  been  proved  by  the  results  of  carefully  conducted 
experiments  at  our  own  and  other  experiment  stations,  and  is  also  borne 
out  by  the  experience  of  practical  dairy  farmers  in  all  parts  of  the  country 
during  the  past  dozen  years  or  more.  At  the  present  time  there  are 
eight  different  makes  of  milking  machines  on  the  market  in  this  state, 
any  one  of  which  may  be  confidently  expected  to  do  satisfactory  work 
in  the  hands  of  a  careful  operator.  Failures  in  machine-milking  have 
been  rather  numerous  in  the  past,  from  a  variety  of  causes,  chief  among 
them  being  perhaps  the  fact  that  the  owner  did  not  fully  understand 
the  mechanics  of  the  machines  or  appreciate  the  necessity  of  care  in 
operating  and  keeping  them  clean,  or  of  following  up  the  machine-milk- 
ing promptly  by  careful  stripping.  Of  late  years  the  failures  have, 
however,  greatly  decreased  in  number,  as  the  machines  have  been  further 
improved  in  simplicity  and  efficiency,  and  the  conditions  for  their  suc- 
cessful operation  are  better  understood.  It  is  safe  to  say  that  a  dairy- 
man who  introduces  machine-milking  into  his  herd  with  any  standard 
make  of  machine  on  the  market  is  now  as  much  on  trial  himself  as  is  the 
machine.  The  best  remedy  for  failures  in  machine-milking  is  to  become 
thoroughly  familiar  with  the  machine  adopted,  its  adaptation  to  in- 
dividual cows,  and  the  requirements  for  keeping  it  in  a  mechanically 
perfect  and  sanitary  condition. 


52  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Milking-machines  have  not  as  yet  been  as  generally  adopted  in 
the  dairy  districts  of  our  country  as,  for  instance,  in  Australia  and  New 
Zealand.  According  to  reliable  reports  received,  there  are  but  few 
dairies  of  over  thirty  cows  in  these  countries  that  are  not  milking 
by  mechanical  means,  and  many  smaller  dairies  are  likewise  using 
milking-machines.  With  the  present  scarcity  of  reliable,  efficient 
milkers,  and  the  high  cost  of  labor,  feed,  and  dairy  supplies,  the  neces- 
sity of  reducing  the  cost  of  milk  production  becomes  greater  than  ever 
before.  It  is  possible  to  do  this  by  either  or  both  of  the  following 
methods :  By  increasing  the  production  of  the  dairy  herd  through  culling, 
use  of  good  pure-bred  sires  and  modern  methods  of  feeding  and  manage- 
ment, or  by  reducing  the  operating  expenses  of  the  dairy.  The  milking- 
machine  is  an  important  aid  in  reducing  these  expenses.  The  days  of 
hand-skimming  of  milk  are  long  gone  by,  and  everything  points  to  the 
fact  that  we  have  now  entered  upon  an  era  of  machine-milking.  It  is 
the  next  step  in  the  economical,  efficient  management  of  fair-sized  or 
large  dairies,  and  the  experience  of  other  dairy  countries  in  regard  to 
milking-machines  will  undoubtedly  be  duplicated  in  this  country. 

The  investigations  of  this  and  other  experiment  stations  have  shown 
that  milking-machines  properly  operated  do  not  injure  the  udders  of 
cows,  or  cause  garget  or  other  udder  diseases.  Udder  troubles  are 
often  due  to  causes  that  are  not  in  any  way  associated  with  the  method 
of  milking  practiced;  they  will  occur  at  times  in  machine-milked,  as 
well  as  in  hand-milked  herds,  although  less  frequently  when  ordinary 
care  is  taken  in  operating  the  machine.  The  best  way  to  avoid  troubles 
of  this  kind  in  case  of  machine-milking  is  to  remove  the  machine  as 
soon  as  no  more  milk  comes  down,  and  to  finish  the  milking  by  hand 
without  unnecessary  delay.  Prompt  and  careful  hand  stripping  is  a 
most  important  factor  in  successful  machine-milking,  even  though  the 
machine  used  leaves  only  very  small  amounts  of  milk  to  be  stripped  out. 

In  the  selection  of  the  particular  make  of  machine,  a  number  of 
points  should  receive  consideration,  besides  first  cost  and  nearness  to 
service  agency,  such  as  cost  of  up-keep,  depreciation,  simplicity  of 
mechanism  and  of  cleaning.  The  various  machines  on  the  market 
differ  considerably  with  regard  to  these  points,  and  it  is  evident  that 
no  one  machine  stands  out  above  the  others  in  all  respects;  also  that 
any  farmer  with  a  fair  degree  of  intelligence  and  resourcefulness  need 
not  hesitate  to  install  a  milking-machine  in  his  dairy  if  he  keeps  twenty 
or  more  cows.  In  many  cases  it  may  prove  advantageous  to  adopt 
machine-milking  also  in  dairies  of  twelve  to  fifteen  cows,  as  it  will  make 
the  owner  less  dependent  upon  or  entirely  independent  of  hired  help. 
The  actual  saving  in  the  cost  of  milking  by  machine  over  hand-milking  is, 


INVESTIGATIONS   WITH    MILKING   MACHINES  53 

however,  greater  in  the  case  of  large  herds  than  with  small  ones  and 
will,  in  general,  be  in  proportion  to  the  size  of  the  herd.  It  has  been 
shown  that  with  proper  care,  and  with  careful,  prompt  hand-stripping, 
milking-machines  will  have  no  appreciable  effect  one  way  or  the  other 
on  the  dairy  production  of  the  cows  or  on  the  general  welfare  of  the  herd, 
but  they  will  not  long  render  satisfactory  service  with  careless  handling 
and  lack  of  cleanliness.  For  this  reason,  milking-machines  are  most 
likely  to  prove  successful  when  operated  by  the  owner  himself  or  by 
help  directly  interested  in  their  success. 


54  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


PARTIAL  BIBLIOGRAPHY  ON  MILKING  MACHINES 

1903— Woll,  "Methods  of  Milking,"  Penn.  Dept.  of  Agriculture,  Bulletin  113,  pp. 

84-96. 
1906— Erf,  "Milking  Machines,"  Kansas  Station  Bulletin  140. 
1907 — Beach,  Stocking  and  Mason,  "Milking  Machines:  effect  upon  quality  and 
yield  of  milk,"  Conn.  (Storrs)  Station  Bulletin  47. 
Lane  and  Stocking,  "The  Milking  Machine  as  a  Factor  in  Dairying,"  U.  S. 

Dept.  of  Agriculture,  Bureau  of  Animal  Industry,  Bulletin  92. 
Dean  and  Edwards,    "Milking  Machines,"   Ontario  Dept.  of  Agriculture 
Bulletin  159. 
1908— Haecker  and  Little,  "Milking  Machines,"  Neb.  Station  Bulletin  108. 
Mairs,  "Test  of  a  Mechanical  Cow  Milker,"  Penn.  Station  Bulletin  85. 
Price,  "Home-grown  rations  in  Economical  Production  of  Milk  and  Butter," 
Tenn.  Station  Bulletin  80. 
1909— Harding,  Wilson  and  Smith,  "Milking  Machines:  effect  of  Methods  of  Milk- 
ing on  the  Germ  Content  of  the  Milk,"  Geneva  (N.Y.)  Experiment  Station 
Bulletin  317. 
Woll  and  Humphrey,  "Milking  Machine  Experiments,"  Wis.  Station  Bul- 
letin 173. 
Woll  and  Humphrey,  "The  Efficiency,  Economy  and  Physiological  Effect 
of  Machine  Milking,"  Wis.  Station  Research  Bulletin  No.  3. 
1912— Smith  and  Harding,  "Milking  Machines:  Effect  of  Machine  Method  of  Milk- 
ing on  Milk  Flow,"  Geneva  (New  York)  Station  Bulletin  353. 
1913 — Wing,  "Milking  Machines:  Their  sterilization  and  their  efficiency  in  produc- 
ing Clean  Milk,"  Cornell  (New  York)  Station  Circular  18. 
Van  Norman,   "Sharpies  Milking  Machine";  Report,  Penn.  State  College 

1912-1913,  pp.  163-164. 
Larsen,  White  and  Fuller,  "Preliminary  Report  on  the  Milking  Machine," 
South  Dakota  Station  Bulletin  144. 
1914 — Hooper  and  Nutter,  "Experiments  with  the  Sharpies  Mechanical  Milker," 

Kentucky  Bulletin  186. 
1915 — Archibald,  "Milking  Machines";  Experimental  Farms,  Ottawa,  Report  1915, 

Vol.  1,  pp.  406-410. 
1916 — Robertson  and  Gilbert,  "Milking  Machines:  A  Study  of  the  Practical  Opera- 
tion of  108  Milking  Machines,"  Jefferson  Co.  (New  York)  Farm  Bureau 
Bulletin  7. 
Larsen,  "Important  Factors  affecting  Machine  Milking,"  S.  Dakota  Bulletin 

166. 
Humphrey,  "Labor  Requirements  of  Dairy  Farms  as  influenced  by  Milking 
Machines,"  U.  S.  Dept.  of  Agriculture,  Bulletin  423. 
1918 — Ruehle  et  al,  "Control  of  Bacteria  in  Milking  Machines,"  Geneva  (New  York) 
Bulletin  415. 
Ruehle  et  al,  "Milking  Machines:  III.  As  a  Source  of  Bacteria  in  Milk;  IV. 
Methods  of  Maintaining  in  a  Bacteria-free  Condition,"  Geneva  (New 
York)  Bulletin  450. 
1919— Riddell,  "Machine  vs.  Hand-Milking,"  Mich.  Quart.  Bulletin,  Vol.  I,  No.  4. 
Hart,  "Importance  of  Sterilization  in  the  Successful  Operation  of  Milking 
Machines,"  Pac.  Dairy  Review,  Vol.  23,  No.  26,  pp.  12-15. 


STATION  PUBLICATIONS  AVAILABLE  FOR  FREE  DISTRIBUTION 


No. 
168. 

169. 
174. 

185. 

208. 
216. 


230. 
242. 
250. 
251. 


252. 
253. 

255. 
257. 
261. 

262. 

263. 
264. 
266. 


267. 
268. 
270. 


271. 
272. 
273. 

274. 

275. 

276. 

277. 


No. 
50. 
65. 


Observations  on  Some  Vine  Diseases 
in   Sonoma   County. 

Tolerance  of  the  Sugar  Beet  for  Alkali. 

A  New  Wine  Cooling  Machine. 

Report  of  Progress  in  Cereal  Investi- 
gations. 

The  Late  Blight  of  Celery. 

A  Progress  Report  upon  Soil  and  Cli- 
matic Factors  Influencing  the  Com- 
position of  Wheat. 

Enological  Investigations. 

Humus  in  California  Soils. 

The  Loquat. 

Utilization  of  the  Nitrogen  and  Organio 
Matter  in  Septic  and  Imhoff  Tank 
Sludges. 

Deterioration  of  Lumber. 

Irrigation  and  Soil  Conditions  in  the 
Sierra    Nevada   Foothills,    California. 

The  Citricola  Scale. 

New  Dosage   Tables^ 

Melaxuma  of  the  Walnut,  "Juglans 
regia." 

Citrus  Diseases  of  Florida  and  Cuba 
Compared  with  Those  of  California. 

Size  Grades  for  Ripe  Olives. 

The  Calibration  of  the  Leakage  Meter. 

A  Spotting  of  Citrus  Fruits  Due  to  the 
Action  of  Oil  Liberated  from  the 
Rind. 

Experiments  with  Stocks  for  Citrus. 

Growing  and  Grafting  Olive  Seedlings. 

A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 
on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California. 

Commercial  Fertilizers. 

Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain. 

The  Common  Honey  Bee  as  an  Agent 
in  Prune  Pollination. 

The  Cultivation  of  Belladonna  in  Cali- 
fornia. 

The  Pomegranate. 

Sudan  Grass. 


BULLETINS 

No. 
278. 
279. 
280. 


281. 
282. 

283. 

284. 
285. 
286. 
288. 

290. 

292. 

293. 
296. 
297. 
298. 
299. 

300. 
301. 

302. 

303. 
304. 

305. 

306. 
307. 
308. 


309. 

310. 
311. 
312. 


CIRCULARS 


70. 


76. 

82. 


87. 
107. 


109. 


110. 
111. 

113. 
114. 
115. 
117. 

124. 
126. 
127. 
128. 
129. 
130. 
131. 
133. 
135. 


Fumigation  Scheduling. 

The  California  Insecticide  Law. 

The  Extermination  of  Morning-Glory. 

Observations  on  the  Status  of  Corn 
Growing  in  California. 

Hot  Room  Callusing. 

The  Common  Ground  Squirrels  of 
California. 

Alfalfa. 

Spraying  Walnut  Trees  for  Blight  and 
Aphis  Control. 

Community  or  Local  Extension  Work 
by  the  High  School  Agricultural  De- 
partment. 

Green  Manuring  in  California. 

The  Use  of  Lime  and  Gypsum  on  Cali- 
fornia  Soils. 

Correspondence  Courses  in  Agriculture. 

Increasing  the  Duty  of  Water. 

Grafting  Vinifera  Vineyards. 

The  Selection  and  Cost  of  a  Small 
Pumping  Plant. 

Alfalfa  Silage  for  Fattening  Steers. 

Spraying  for  the  Grape  Leaf  Hopper. 

House  Fumigation. 

Insecticide  Formulas. 

The  Control  of  Citrus  Insects. 

Cabbage  Growing  in  California. 

Spraying  for  Control  of  Walnut  Aphis. 

County  Farm  Adviser. 

Official  Tests  of  Dairy  Cows. 


No. 
136. 
137. 
138. 
139. 


140. 


142. 

143. 

144. 
147. 
148. 
151. 
152. 

153. 

154. 

155. 

156. 
157. 
158. 
160. 
162. 

164. 


Grain   Sorghums. 

Irrigation  of  Rice  in  California. 

Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

Control  of  the  Pocket  Gopher  in  Cali- 
fornia. 

Trials  with  California  Silage  Crops  for 
Dairy  Cows. 

The  Olive  Insects  of  California. 

Irrigation  of  Alfalfa  in  Imperial  Valley. 

The  Milch  Goat  in  California. 

Commercial  Fertilizers. 

Potash  from  Tule  and  the  Fertilizer 
Value  of  Certain  Marsh  Plants. 

The  June  Drop  of  Washington  Navel 
Oranges. 

Green  Manure  Crops  in  Southern  Cali- 
fornia. 

Sweet  Sorghums  for  Forage. 

Topping  and  Pinching  Vines. 

The  Almond  in  California. 

Seedless  Raisin  Grapes. 

The  Use  of  Lumber  on  California 
Farms. 

Commercial  Fertilizers. 

California  State  Dairy  Cow  Competi- 
tion, 1916-18. 

Control  of  Ground  Squirrels  by  the 
Fumigation  Method. 

Grape  Syrup. 

A  Study  on  the  Effects  of  Freezes  on 
Citrus  in  California. 

The  Influence  of  Barley  on  the  Milk 
Secretion  of  Cows. 

Almond  Pollination. 

Pollination  of  the  Bartlett  Pear. 

I.  Fumigation  with  Liquid  Hydrocianic 
Acid.  II.  Physical  and  Chemical 
Properties  of  Liquid  Hydrocianic 
Acid. 

I.  The  Carob  in  California.  II.  Nutri- 
tive Value  of  the  Carob  Bean. 

Plum  Pollination. 

Investigations  with  Milking  Machines. 

Mariout  Barley. 


Melilotus  Indica. 

Wood  Decay  in  Orchard  Trees. 

The  Silo  in  California  Agriculture. 

The  Generation  of  Hydrocyanic  Acid 
Gas  in  Fumigation  by  Portable 
Machines. 

The  Practical  Application  of  Improved 
Methods  of  Fermentation  in  Califor- 
nia Wineries  during  1913  and  1914. 

Practical  and  Inexpensive  Poultry 
Appliances. 

Control  of  Grasshoppers  in  Imperial 
Valley. 

Oidium  or  Powdery  Mildew  of  the  Vine. 

Tomato  Growing  in  California. 

"Lungworms". 

Feeding  and  Management  of  Hogs. 

Some  Observations  on  the  Bulk  Hand- 
ling of  Grain  in  California. 

Announcement  of  the  California  State 
Dairy  Cow  Competition,  1916-18. 

Irrigation  Practice  in  Growing  Small 
Fruits  in  California. 

Bovine  Tuberculosis. 

How  to  Operate  an  Incubator. 

Control  of  the  Pear  Scab. 

Home  and  Farm  Canning. 

Lettuce  Growing  in  California. 

White  Diarrhoea  and  Coccidiosis  of 
Chicks. 

Small  Fruit  Culture  in  California. 


CIRCULARS — Continued 


No.  No. 

165.  Fundamentals   of   Sugar   Beet   Culture  189. 

under  California  Conditions.  190. 

166.  The  County  Farm  Bureau.  191. 

167.  Feeding  Stuffs  of  Minor  Importance.  193. 

168.  Spraying    for     the     Control     of     Wild  195. 

Morning-Glory  within  the  Fog  Belt. 

169.  The    1918   Grain   Crop.  197. 

170.  Fertilizing     California     Soils     for     the 

1918   Crop.  198. 

172.  Wheat  Culture.  199. 

173.  The    Construction    of    the    Wood-Hoop  200. 

Silo. 

174.  Farm  Drainage  Methods.  201. 

175.  Progress  Report  on  the  Marketing  and  202. 

Distribution  of  Milk. 

176.  Hog  Cholera  Prevention  and  the  Serum  203. 

Treatment.  204. 

177.  Grain    Sorghums. 

178.  The  Packing  of  Apples  in  California.  205. 

179.  Factors   of     Importance   in    Producing  206. 

Milk  of  Low  Bacterial   Count.  207. 

181.  Control     of      the     California     Ground  208. 

Squirrel. 

182.  Extending  the  Area  of  Irrigated  Wheat  209. 

in  California  for  1918.  210. 

183.  Infectious  Abortion  in   Cows.  211, 

184.  A  Flock  of  Sheep  on  the  Farm.  212. 

185.  Beekeeping   for   the    Fruit-grower    and  213. 

Small  Rancher  or  Amateur.  214. 

187.  Utilizing  the   Sorghums. 

188.  Lambing  Sheds.  215. 


Winter  Forage  Crops. 

Agriculture  Clubs  in  California. 

Pruning  the  Seedless  Grapes. 

A  Study  of  Farm  Labor  in  California. 

Revised  Compatibility  Chart  of  Insecti- 
cides and  Fungicides. 

Suggestions  for  Increasing  Egg  Produc- 
tion in  a  Time  of  High-Feed  Prices. 

Syrup  from   Sweet  Sorghum. 

Onion   Growing  in  California. 

Growing  the  Fall  or  Second  Crop  of 
Potatoes  in  California. 

Helpful  Hints  to  Hog  Raisers. 

County  Organization  for  Rural  Fire 
Control. 

Peat  as  a  Manure   Substitute. 

Handbook  of  Plant  Diseases  and  Pest 
Control. 

Blackleg. 

Jack  Cheese. 

Neufchatel  Cheese. 

Summary  of  the  Annual  Reports  of  the 
Farm  Advisors  of  California. 

The  Function  of  the  Farm  Bureau. 

Suggestions  to  the  Settler  in  California. 

Saving  Raisins  by  Sulfuring. 

Salvaging  Rain-Damaged  Prunes. 

Evaporators  for  Prune  Drying. 

Seed  Treatment  for  the  Prevention  of 
Cereal   Smuts. 

Feeding  Dairy  Cows  in  California. 


